It is proposed to prepare the basic tetracyclic ring system of the antileukemic alkaloid pseudolycorine by application of gamma-alkylations of enaminoketones in an intramolecular process. The remaining functional group modifications necessary to complete the pseudolycorine structure are approached through use of sulfur and selenium chemistry. Alternative modes of synthesis are also provided. In addition, it is also proposed to construct encelin, a sesquiterpene lactone exhibiting strong anticancer activity. Encelin is to be prepared by the gamma-carbanion alkylation of simple enaminoketones followed by a cyclodehydration to yield the bicyclic ring system of this compound. Enamine addition and functional group modifications will provide this sesquiterpene drug. Alternative synthetic routes are proposed and the successful completion of an encelin synthesis should allow for initiation of studies of more complex sesquiterpenes such as paucin or venolepin and others. BIBLIOGRAPHIC REFERENCES: Vinylogous Thioester Chemistry: The Total Synthesis of Desmethyl-Beta-Cyperone, R. B. Gammill and T. A. Bryson, Tet. Let., 3793 (1975). Synthesis of alpha-Methylene-gamma-Butyrolactones, R. B. Gammill, C. A. Wilson, and T. A. Bryson, Synthetic Communications, 5, 245 (1975).